A large amount of oil is expressed from oil seed leaving a solids residue or cake. The cake contains usable protein values and is generally used as is as a supplement to animal feed. The protein values have also been extracted to provide a high protein content material for use in human food. The protein has been used as a protein fortifier additive as well as in some functional capacity. However, less expensive oil seed proteins have not been used substantially as substitutes for high cost functional proteins such as sodium caseinate.
Sodium caseinate is a solubilized form of the protein casein. Casein is insoluble at its isoelectric point. Both are non-gelable upon heating. Sodium caseinate has found extensive use in foods as it imparts creaminess, firmness and smoothness to the consistency of products, thermoplasticity to imitation cheese, high buffering capacity to products such as coffee whiteners, and emulsifying and water absorption effects in addition to its nutritional value. Sodium caseinate is also effective as a binder or extender in meats, soups and the like.
It is known in accordance with EPO Publication No. 0029370 published 5/27/81, that the thermogelation temperature of a protein which is soluble under alkaline pH and at its isoelectric point, such as whey protein, (dairy or soy) can be reduced by heating the protein in solution at an alkaline pH of 7.5 to 10, at a temperature above 50.degree. C. and below the gelation temperature, cooling the heated solution before the protein gels and reducing the pH to neutral. The reference specifically states that protein which is insoluble at alkaline pH cannot be made soluble. The teachings of this reference are directed to lowering the thermogelation temperature of a thermogelable protein or as a corollary increasing the gel strength when heated under normal gelation conditions. The proteins treated in accordance with the process of the reference are the proteins soluble at the isoelectric point, the reference being particularly directed to dairy whey protein.
It is the intent of the invention to provide processes for improving the functionality of vegetable protein including oil seed protein and particularly for providing protein evidencing increased functionality including increased solution viscosity.